A rapid atmospheric-pressure pulsed helium/hydrogen plasma jet method for conversion of TiO₂ films into defective, black TiO₂ is demonstrated. This method can reduce nanoporous anatase films with fine spatial control, allowing precise 2D patterning of pre-deposited films under ambient conditions. The resulting modified TiO₂ films are stable in air and show enhanced photocatalytic activity with respect to the as-deposited films. From photoelectrochemical current measurements, the plasma-treated anatase TiO₂ films supported on FTO-glass showed a six-fold increase in photocurrent density under both sub- and super-bandgap illumination compared to untreated anatase films. The changes in optical absorption are mainly due to introduced mid-gap states, with negligible overall band gap narrowing. Thorough characterisation of these black TiO₂ materials using X-ray photoelectron, Raman and UV-VIS spectroscopy showed strong evidence for the presence of Ti³⁺ states in the reduced films. There is a clear relationship between the Ti³⁺ content of the plasma-treated TiO₂ and the enhanced photocurrent, although increased Ti³⁺ content leads to a decrease in photocurrent, which we ascribe to an increase in the number of electron–hole recombination centres.